351
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Delgado N, Xue J, Yu JJ, Hung CY, Cole GT. A recombinant beta-1,3-glucanosyltransferase homolog of Coccidioides posadasii protects mice against coccidioidomycosis. Infect Immun 2003; 71:3010-9. [PMID: 12761077 PMCID: PMC155699 DOI: 10.1128/iai.71.6.3010-3019.2003] [Citation(s) in RCA: 56] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/07/2003] [Revised: 02/11/2003] [Accepted: 02/20/2003] [Indexed: 11/20/2022] Open
Abstract
Coccidioides posadasii is a fungal respiratory pathogen which is responsible for recurrent epidemics of San Joaquin Valley fever (coccidioidomycosis) in desert regions of the southwestern United States. Numerous studies have revealed that the cell wall of the parasitic phase of the fungus is a reservoir of immunoreactive macromolecules and a potential source of a vaccine against this mycosis. A 495-bp fragment of a C. posadasii gene which encodes a putative wall-associated, glycosylphosphatidylinositol (GPI)-anchored beta-1,3-glucanosyltransferase was identified by computational analysis of the partially sequenced genome of this pathogen. The translated, full-length gene (GEL1) showed high sequence homology to a reported beta-1,3-glucanosyltransferase of Aspergillus fumigatus (70% identity, 90% similarity) and was selected for further study. The GEL1 mRNA of C. posadasii was detected at the highest level during the endosporulation stage of the parasitic cycle, and the mature protein was immunolocalized to the surface of endospores. BALB/c or C57BL/6 mice were immunized subcutaneously with the bacterium-expressed recombinant protein (rGel1p) to evaluate its protective efficacy against a lethal challenge of C. posadasii by either the intraperitoneal or intranasal route. In both cases, rGel1p-immune mice infected with the pathogen showed a significant reduction in fungal burden and increased survival compared to nonimmune mice. The recombinant beta-1,3-glucanosyltransferase is a valuable addition to an arsenal of immunoreactive proteins which could be incorporated into a human vaccine against coccidioidomycosis.
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Affiliation(s)
- Nelson Delgado
- Department of Microbiology and Immunology, Medical College of Ohio, Toledo 43614, USA
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352
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Ellis JT, Morrison DA, Reichel MP. Genomics and its impact on parasitology and the potential for development of new parasite control methods. DNA Cell Biol 2003; 22:395-403. [PMID: 12906733 DOI: 10.1089/104454903767650667] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
Parasitic organisms remain the scourge of the developed and underdeveloped worlds. Malaria, schistosomiasis, leishmaniasis, and trypanosomiasis, for example, still result in a large number of human deaths each year worldwide, while drug resistance among nematodes still poses a major problem to the livestock industries. Genome projects involving parasitic organisms are now abundant, and technologies for the investigations of the parasite transcriptome and proteome are well established. There is no doubt the era of the "omics" is with parasitology, and current trends in the discipline are addressing fundamental biological questions that can make best use of the new technologies, as well as the vast amount of new data being generated. Will this become the "golden age of molecular parasitology," leading to the control of parasitic diseases that have plagued mankind for hundreds of years? The primary aim of this paper is to review advances in the general area of parasite genomics, and to outline where the application of "omics" technologies can and have impacted on the development of new control methods for parasitic organisms.
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Affiliation(s)
- John T Ellis
- Institute for the Biotechnology of Infectious Diseases, University of Technology, Sydney, Gore Hill, NSW 2065, Australia.
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353
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Abstract
Cells expressing Toll-like receptor (TLR), TLR2 in association with TLR1, TLR6 or some other unknown co-receptor can respond upon interaction with a large variety of microbial ligands. The variety of TLR2 ligands is the greatest among all the TLRs and this is due to the heterodimerization needed for TLR2 mediated responses. Like other TLRs, TLR2 signaling induces antigen presenting cell activation, pro-inflammatory cytokine production and increased expression of co-stimulatory ligand expression. These events are important for induction of innate immune responses and improved acquired immunity. There is strong suggestive evidence that alteration or lack of TLR2 function in vivo may correlate to decreased immune protection from pathogens that contain TLR2 ligands, but more work needs to be performed to strengthen this correlation.
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Affiliation(s)
- Lee M Wetzler
- Department of Medicine, Division of Infectious Diseases, Boston Medical Center, Boston University School of Medicine, Evans Biomedical Research Center, Boston, MA 02118, USA.
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354
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Means TK, Hayashi F, Smith KD, Aderem A, Luster AD. The Toll-like receptor 5 stimulus bacterial flagellin induces maturation and chemokine production in human dendritic cells. JOURNAL OF IMMUNOLOGY (BALTIMORE, MD. : 1950) 2003; 170:5165-75. [PMID: 12734364 DOI: 10.4049/jimmunol.170.10.5165] [Citation(s) in RCA: 304] [Impact Index Per Article: 14.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Abstract
Toll-like receptors (TLRs) are pattern recognition receptors that serve an important function in detecting pathogens and initiating inflammatory responses. Upon encounter with foreign Ag, dendritic cells (DCs) go through a maturation process characterized by an increase in surface expression of MHC class II and costimulatory molecules, which leads to initiation of an effective immune response in naive T cells. The innate immune response to bacterial flagellin is mediated by TLR5, which is expressed on human DCs. Therefore, we sought to investigate whether flagellin could induce DC maturation. Immature DCs were cultured in the absence or presence of flagellin and monitored for expression of cell surface maturation markers. Stimulation with flagellin induced increased surface expression of CD83, CD80, CD86, MHC class II, and the lymph node-homing chemokine receptor CCR7. Flagellin stimulated the expression of chemokines active on neutrophils (IL-8/CXC chemokine ligand (CXCL)8, GRO-alpha/CXCL1, GRO-beta/CXCL2, GRO-gamma/CXCL3), monocytes (monocyte chemoattractant protein-1/CC chemokine ligand (CCL)2), and immature DCs (macrophage-inflammatory protein-1 alpha/CCL3, macrophage-inflammatory protein-1 beta/CCL4), but not chemokines active on effector T cells (IFN-inducible protein-10 kDa/CXCL10, monokine induced by IFN-gamma/CXCL9, IFN-inducible T cell alpha chemoattractant/CXCL11). However, stimulating DCs with both flagellin and IFN-inducible protein-10 kDa, monokine induced by IFN-gamma, and IFN-inducible T cell alpha chemoattractant expression, whereas stimulation with IFN-beta or flagellin alone failed to induce these chemokines. In functional assays, flagellin-matured DCs displayed enhanced T cell stimulatory activity with a concomitant decrease in endocytic activity. Finally, DCs isolated from mouse spleens or bone marrows were shown to not express TLR5 and were not responsive to flagellin stimulation. These results demonstrate that flagellin can directly stimulate human but not murine DC maturation, providing an additional mechanism by which motile bacteria can initiate an acquired immune response.
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Affiliation(s)
- Terry K Means
- Center for Immunology and Inflammatory Diseases and Division of Rheumatology, Allergy and Immunology, Massachusetts General Hospital and Harvard Medical School, Boston, MA 02129, USA
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355
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356
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Andersson J, Orn A, Sunnemark D. Chronic murine Chagas' disease: the impact of host and parasite genotypes. Immunol Lett 2003; 86:207-12. [PMID: 12644324 DOI: 10.1016/s0165-2478(03)00019-1] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Chagas' disease is a protozoan infection caused by the flagellate Trypanosoma cruzi. Herein we utilise experimental infections of different mouse and parasite strains to investigate the relative importance of the host and parasite genotype, respectively, in causing Chagas' disease in mice. CBA/J and BALB/c mice infected with the Tulahuen strain of T. cruzi develop a severe acute disease characterised by transient parasitaemia and a high rate of mortality. While the acute phases in these mice are indistinguishable, they display differential outcomes of the infection since CBA/J mice eventually develop polymyositis and mild myocarditis whereas BALB/c mice are resistant to chronic disease. In contrast, BALB/c mice infected with the CA-1 clone of T. cruzi exhibit a mild acute phase, develop no polymyositis but do develop severe myocarditis. Thus both the parasite and host genotype, but not the severity of the acute phase, are important in determining the eventual outcome of T. cruzi infection. We also present a murine model suitable for investigating which host factors may be necessary to induce a chronic inflammatory disease after T. cruzi infection.
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Affiliation(s)
- John Andersson
- Microbiology and Tumor Biology Center, Karolinska Institutet, P.O. Box 280, S-171 77, Stockholm, Sweden.
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357
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Qureshi ST, Medzhitov R. Toll-like receptors and their role in experimental models of microbial infection. Genes Immun 2003; 4:87-94. [PMID: 12618855 DOI: 10.1038/sj.gene.6363937] [Citation(s) in RCA: 104] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
Effective host defense against microbial infection depends upon prompt recognition of pathogens, activation of immediate containment measures, and ultimately the generation of a specific and definitive adaptive immune response. The innate immune system of the host is responsible for providing constant surveillance against infection; when confronted by pathogens it deploys a series of rapidly acting antimicrobial effectors while simultaneously instructing the adaptive immune system as to the nature and context of the infectious threat. Pathogen recognition and activation of innate immunity is mediated by members of the Toll-like receptor (TLR) family through detection of conserved microbial structures that are absent from the host. Experimental models of infection using TLR-deficient mice, as well as limited human studies, have clearly demonstrated the critical role of TLRs in host defense against most major groups of mammalian pathogens.
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Affiliation(s)
- Salman T Qureshi
- Section of Immunology, Yale University School of Medicine, New Haven, CT 06510, USA.
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358
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Dunne A, O'Neill LAJ. The Interleukin-1 Receptor/Toll-Like Receptor Superfamily: Signal Transduction During Inflammation and Host Defense. Sci Signal 2003. [DOI: 10.1126/scisignal.1712003re3] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
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359
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Dunne A, O'Neill LAJ. The interleukin-1 receptor/Toll-like receptor superfamily: signal transduction during inflammation and host defense. SCIENCE'S STKE : SIGNAL TRANSDUCTION KNOWLEDGE ENVIRONMENT 2003; 2003:re3. [PMID: 12606705 DOI: 10.1126/stke.2003.171.re3] [Citation(s) in RCA: 347] [Impact Index Per Article: 16.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
Abstract
The signal transduction pathways activated by the proinflammatory cytokine interleukin-1 (IL-1) have been the focus of much attention because of the important role that IL-1 plays in inflammatory diseases. A number of proteins have been described that participate in the post-receptor activation of the transcription factor nuclear factor kappaB (NF-kappaB), and stress-activated protein kinases such as p38 mitogen-activated protein kinase (MAPK). It has also emerged that the type I IL-1 receptor (IL-1RI) is a member of an expanding receptor superfamily. These related receptors all have sequence similarity in their cytosolic regions. The family includes the Drosophila melanogaster protein Toll, the IL-18 receptor (IL-18R), and 10 Toll-like receptors (TLRs), TLR-1 to TLR-10, which bind to microbial products, activating host defense responses. Because of the similarity of IL-1RI to Toll, the conserved sequence in the cytosolic region of these proteins has been termed the Toll-IL-1 receptor (TIR) domain. The same proteins activated during signaling by IL-1RI also participate in signaling by other receptors with TIR domains. The receptor superfamily is evolutionarily conserved; members also occur in plants and insects, where they also function in host defense. The signaling proteins that are activated are also conserved across species. Differences are, however, starting to emerge in signaling pathways activated by different receptors. This receptor superfamily, therefore, represents an ancient signaling system that is a critical determinant of the innate immune and inflammatory responses.
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Affiliation(s)
- Aisling Dunne
- Department of Biochemistry and Biotechnology Institute, Trinity College, Dublin, Ireland
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360
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Denkers EY, Kim L, Butcher BA. In the belly of the beast: subversion of macrophage proinflammatory signalling cascades during Toxoplasma gondii infection. Cell Microbiol 2003; 5:75-83. [PMID: 12580944 DOI: 10.1046/j.1462-5822.2003.00258.x] [Citation(s) in RCA: 57] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
Macrophages (MØ) are used as the intracellular niche by several bacterial and protozoan microorganisms. Such microbial pathogens adopt diverse strategies to avoid MØ microbicidal effects. Recent insights into the Toxoplasma gondii-MØ interaction reveal novel ways that intracellular parasites subvert MØ function. In contrast to some microbial pathogens, Toxoplasma infection is not silent but induces rapid activation of transcription factors such as STAT-1 and NFkappaB. However, the parasite blocks nuclear translocation of both factors, and MØ cannot produce IL-12 or TNF-alpha when subsequently triggered with lipopolysaccharide. The nuclear import blockade is lifted 24 h after infection, but cells remain actively suppressed in TNF-alpha production. Nevertheless, IL-12 synthesis is initiated at this later time point. Toxoplasma gondii-induced production of this cytokine occurs through both MyD88- and CCR5-dependent pathways. The balance of cytokine subversion and stimulation during infection probably results from the parasite's need to simultaneously avoid immune elimination and trigger immunity to prevent host death.
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Affiliation(s)
- Eric Y Denkers
- Department of Microbiology and Immunology, College of Veterinary Medicine, Cornell University, Ithaca, NY 14853-6401, USA.
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361
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Abstract
Toll-like receptors (TLRs) are type I transmembrane proteins involved in innate immunity by recognizing microbial conserved structures. Recent studies have shown that TLR3 recognizes dsRNA, a viral product, whereas TLR9 recognizes unmethylated CpG motifs frequently found in the genome of bacteria and viruses, but not vertebrates. TLR7 recognizes small synthetic immune modifiers including imiquimod, R-848, loxoribine, and bropirimine, all of which are already applied or promising for clinical use against viral infections and cancers. Plasmacytoid dendritic cells express TLR7 and TLR9, and respond to TLR7 and TLR9 ligands by producing a large amount of interferon (IFN-alpha). These results indicate that TLR3, TLR7 and TLR9 may play an important role in detecting and combating viral infections.
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Affiliation(s)
- Shizuo Akira
- Department of Host Defense, Research Institute for Microbial Diseases, Osaka University, SORST of Japan Science and Technology Corporation, 3-1 Yamada-oka, Suita, Osaka 565-0871, Japan.
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362
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Abstract
Invading pathogens are controlled by the innate and adaptive arms of the immune system. Adaptive immunity, which is mediated by B and T lymphocytes, recognises pathogens by rearranged high affinity receptors. However, the establishment of adaptive immunity is often not rapid enough to eradicate microorganisms as it involves cell proliferation, gene activation and protein synthesis. More rapid defense mechanisms are provided by innate immunity, which recognises invading pathogens by germ-line-encoded pattern recognition receptors (PRR). Recent evidence shows that this recognition can mainly be attributed to the family of TOLL-like receptors (TLR). Binding of pathogen-associated molecular patterns (PAMP) to TLR induces the production of reactive oxygen and nitrogen intermediates (ROI and RNI), pro-inflammatory cytokines, and up-regulates expression of co-stimulatory molecules, subsequently initiating the adaptive immunity. In this review, we will summarize the discovery and the critical roles of the TLR family in host defense, briefly allude to signaling mechanisms mediating the response to TLR ligands, and will provide an update on current knowledge regarding the ligand specificity of these receptors and their role in immunity of domestic animals, particularly cattle.
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Affiliation(s)
- Dirk Werling
- Institute of Veterinary Virology, University of Berne, Länggass-Str. 122, CH-3012 Bern, Switzerland
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363
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Abstract
The Toll-like receptors (TLRs) are key molecules involved in the recognition of pathogens by the innate immune system. This family of germ line-encoded receptors has evolved to recognize conserved features of microbes. Currently, 10 TLR family members have been identified in mammals. The number of ligands for these receptors continues to grow, and it seems clear that multiple ligands exist for each receptor. Whether engagement of different TLRs leads to differences in gene expression and thereby differences in the immune response remains to be seen. However, recent work has demonstrated that activation of TLRs is required for initiation of only certain adaptive immune responses.
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Affiliation(s)
- G M Barton
- Section of Immunobiology, Howard Hughes Medical Institute, Yale University School of Medicine, 310 Cedar St., BML 458, New Haven, CT 06520, USA.
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364
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Kirschning CJ, Schumann RR. TLR2: cellular sensor for microbial and endogenous molecular patterns. Curr Top Microbiol Immunol 2003; 270:121-44. [PMID: 12467248 DOI: 10.1007/978-3-642-59430-4_8] [Citation(s) in RCA: 95] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
Toll-like receptor (TLR) 2 is a member of the vertebrate protein family of TLRs that has been studied in substantial detail over the last years. The extracellular domain of the type I receptor molecule TLR2 contains 18 to 20 leucine rich repeat (LRR) and LRR like motives. The intracellular domain of TLR2 contains a Toll/IL-1 receptor/resistance protein typical TIR domain. After the first implication of TLR4 in immunity thereinafter followed by the discovery of the lipopolysaccharide signal transducer function of TLR4, TLR2 was the first of ten mammalian TLRs proven to be directly involved in recognition of pathogen associated molecular patterns (PAMPs). Among the TLR2 specific agonists are microbial products representing broad groups of species such as Gram-positive and Gram-negative bacteria, as well as mycobacteria, spirochetes, and mycoplasm. PAMP induced phagosomal localization of TLR2 and TLR2 dependent apoptosis have been shown. Complex formation with other molecules involved in pattern recognition such as CD14, MD2, TLR1, and TLR6 has been implicated for TLR2. Surprisingly even proteinaceous host material such as heat shock protein (HSP) 60 has been demonstrated to activate cells through TLR2. Thus, TLR2 may be a sensor and inductor of specific defense processes, including oxidative stress and cellular necrosis initially spurred by microbial compounds. Here we summarize the current knowledge on the structure and function of TLR2, which is far from being complete. Detailed understanding of the biology of TLR2 will probably contribute to the characterization of a number of infectious diseases and potentially help in the development of novel intervention strategies.
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Affiliation(s)
- C J Kirschning
- Institute of Medical Microbiology, Immunology, and Hygiene, Technical University of Munich, 81675 Munich, Germany.
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365
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Beschin A, Bilej M, Magez S, Lucas R, De Baetselier P. Functional convergence of invertebrate and vertebrate cytokine-like molecules based on a similar lectin-like activity. PROGRESS IN MOLECULAR AND SUBCELLULAR BIOLOGY 2003; 34:145-63. [PMID: 14979667 DOI: 10.1007/978-3-642-18670-7_6] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/03/2022]
Abstract
It is generally accepted that the action of cytokines results from their binding to specific receptors. However, many cytokines possess lectin-like activity that may be essential for the expression of their full biological activities. This review focuses on the physiological relevance of the lectin-like activity of cytokines during the innate immune response in mammals, using TNF as an illustrative example. Moreover, we will show that TNF displays functional analogies with a defense molecule from the earthworm Eisenia foetida termed CCF. These analogies are not reflected by primary sequence homology between CCF and TNF but are particularly based on a similar lectin-like activity/domain. Hence, from a phylogenetic point of view, the lectin-like activity/domain of CCF and TNF may represent an essential recognition mechanism that has been functionally conserved during the innate immune response of invertebrates and vertebrates as a result of convergent evolution.
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Affiliation(s)
- A Beschin
- Department of Immunology, Parasitology and Ultrastructure, Flemish Interuniversity Institute for Biotechnology, Free University Brussels (VUB), Pleinlaan 2, 1050 Brussels, Belgium
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366
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Ferreira LRP, Abrantes EF, Rodrigues CV, Caetano B, Cerqueira GC, Salim AC, Reis LFL, Gazzinelli RT. Identification and characterization of a novel mouse gene encoding a Ras‐associated guanine nucleotide exchange factor: expression in macrophages and myocarditis elicited by
Trypanosoma cruzi
parasites. J Leukoc Biol 2002. [DOI: 10.1189/jlb.72.6.1215] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022] Open
Affiliation(s)
- Ludmila R. P. Ferreira
- Department of Biochemistry and Immunology, Institute of Biological Sciences, Federal University of Minas Gerais, Brazil
- Centro de Pesquisas René Rachou, Oswaldo Cruz Foundation, Belo Horizonte, MG, Brazil; and
- Ludwig Institute for Cancer Research, São Paulo, SP, Brazil
| | | | - Cibele V. Rodrigues
- Department of Biochemistry and Immunology, Institute of Biological Sciences, Federal University of Minas Gerais, Brazil
| | - Braulia Caetano
- Department of Biochemistry and Immunology, Institute of Biological Sciences, Federal University of Minas Gerais, Brazil
- Centro de Pesquisas René Rachou, Oswaldo Cruz Foundation, Belo Horizonte, MG, Brazil; and
| | - Gustavo C. Cerqueira
- Department of Biochemistry and Immunology, Institute of Biological Sciences, Federal University of Minas Gerais, Brazil
| | | | | | - Ricardo T. Gazzinelli
- Department of Biochemistry and Immunology, Institute of Biological Sciences, Federal University of Minas Gerais, Brazil
- Centro de Pesquisas René Rachou, Oswaldo Cruz Foundation, Belo Horizonte, MG, Brazil; and
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367
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Kawai K, Shimura H, Minagawa M, Ito A, Tomiyama K, Ito M. Expression of functional Toll-like receptor 2 on human epidermal keratinocytes. J Dermatol Sci 2002; 30:185-94. [PMID: 12443841 DOI: 10.1016/s0923-1811(02)00105-6] [Citation(s) in RCA: 108] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023]
Abstract
Epidermal keratinocytes secrete cytokines, chemokines, and anti-microbial peptides in response to various microbial pathogens and their components including lipopolysaccharide (LPS). To identify the receptor(s) involved in the anti-microbial responses of epidermal keratinocytes, we analyzed expression of CD14, Toll-like receptor 2 (TLR2), and TLR4 on cultured normal human epidermal keratinocytes (NHEK). Although CD14 and TLR2 mRNA were expressed in cultured NHEK, only TLR2 was detected on the cell surface. Cultured NHEK did not express TLR4 mRNA or protein. Commercial LPS preparations could stimulate epidermal keratinocytes to produce beta-defensin-2 and IL-8, and the LPS response was inhibited with mAb specific for TLR2, but not for CD14 or TLR4. Repurified LPS and lipid A did not stimulate epidermal keratinocytes, whereas peptidoglycan (PGN) from Gram-positive bacteria and yeast cell wall particle induced beta-defensin-2 and IL-8 production. Thus, cultured NHEK express functional TLR2, but not CD14 or TLR4, and the "LPS" response of epidermal keratinocytes shown in the previous studies might be mediated by TLR2-dependent recognition of non-LPS bacterial components contaminating in commercial LPS preparations. In the normal human skin, however, epidermal keratinocytes expressed both TLR2 and TLR4. Because TLR4 was induced in epidermal keratinocytes by in vitro stimulation with PGN from Gram-positive bacteria, constitutive expression of TLR4 on epidermal keratinocytes in vivo might also be induced by continuous recognition of the resident skin flora containing Gram-positive bacteria through TLR2.
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Affiliation(s)
- Kazuhiro Kawai
- Department of Dermatology, Niigata University School of Medicine, 1-757 Asahimachi-dori, Niigata 951-8510, Japan.
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368
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Hawn TR, Ozinsky A, Underhill DM, Buckner FS, Akira S, Aderem A. Leishmania major activates IL-1 alpha expression in macrophages through a MyD88-dependent pathway. Microbes Infect 2002; 4:763-71. [PMID: 12270723 DOI: 10.1016/s1286-4579(02)01596-4] [Citation(s) in RCA: 63] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Leishmania species present unusual challenges to the immune system with their capacity to downregulate inflammatory responses as well as their ability to live within macrophages. Although toll-like receptor (TLR) pathways have been implicated in the recognition of several classes of pro-inflammatory microbes, it is not known if pathogens with anti-inflammatory properties activate the host response through this family of proteins. In this study, Leishmania major stimulation of cytokine promoter-luciferase reporter constructs was examined in transfected macrophages to detect early signs of cellular activation. L. major selectively activated the promoter region of IL-1 alpha, but not IL-6, IL-8, IL-10, or an NF-kappa B reporter. IL-1 alpha mRNA expression was also stimulated by L. major, although at lower levels than lipopolysacharide-stimulated macrophages. No IL-1 alpha protein was detectable in stimulated cell lysates or culture supernatants. Transfection of macrophages with a dominant-negative version of myeloid differentiation factor 88 (MyD88), an adaptor protein which interacts with TLRs, inhibited activation of the IL-1 alpha promoter. Furthermore, stimulation of IL-1 alpha RNA expression by L. major was inhibited in peritoneal macrophages from MyD88-/- as compared to MyD88+/+ mice. These observations indicate that L. major stimulates IL-1 alpha promoter activity and mRNA expression in macrophages through MyD88-dependent pathways. However, additional anti-inflammatory pathways must also be activated which downregulate transcription and ultimately inhibit translation of the IL-1 alpha protein. Examination of promoter activation is a powerful tool for understanding the early events in macrophage activation for anti-inflammatory pathogens such as Leishmania that have mechanisms to downregulate transcription and translation.
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Affiliation(s)
- Thomas R Hawn
- Division of Infectious Diseases, Department of Medicine, University of Washington, Seattle, WA 98195, USA
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369
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Abstract
Mammalian cell invasion by the protozoan pathogen Trypanosoma cruzi is critical to its survival in the host. To promote its entry into a wide variety of non-professional phagocytic cells, infective trypomastigotes exploit an arsenal of heterogenous surface glycoproteins, secreted proteases and signalling agonists to actively manipulate multiple host cell signalling pathways. Signals initiated in the parasite upon contact with mammalian cells also function as critical regulators of the invasion process. Whereas the full spectrum of cellular responses modulated by T. cruzi is not yet known, mounting evidence suggests that these pathways impinge on a number of cellular processes, in particular the ubiquitous wound-repair mechanism exploited for lysosome-mediated parasite entry. Furthermore, differential engagement of host cell signalling pathways in a cell type-specific manner and modulation of host cell gene expression by T. cruzi are becoming recognized as essential determinants of infectivity and intracellular survival by this pathogen.
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Affiliation(s)
- Barbara A Burleigh
- Department of Immunology and Infectious Diseases, Harvard School of Public Health, 665 Huntington Ave, Bldg I Rm 713, Boston, MA 02115, USA.
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370
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Chen M, Aosai F, Norose K, Mun HS, Takeuchi O, Akira S, Yano A. Involvement of MyD88 in host defense and the down-regulation of anti-heat shock protein 70 autoantibody formation by MyD88 in Toxoplasma gondii-infected mice. J Parasitol 2002; 88:1017-9. [PMID: 12435148 DOI: 10.1645/0022-3395(2002)088[1017:iomihd]2.0.co;2] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022] Open
Abstract
This study investigated the influence of TLR (toll-like receptor)4, TLR2, and MyD88 in Toxoplasma gondii-infected wild-type (WT) mice and TLR4-, TLR2-, and MyD88-deficient mice. Ninety-five percent of MyD88-deficient mice died 10-16 days after intraperitoneal infection with 100 cysts of T. gondii Fukaya strain, whereas 95-100% of TLR4- and TLR2-deficient mice and WT C57BL/6 (B6) mice survived for more than 7 wk after T. gondii infection. The distribution of T. gondii in various organs of TLR4-, TLR2-, and MyD88-deficient mice and WT B6 mice was assessed 2 wk after T. gondii intraperitoneal infection using quantitative competitive polymerase chain reaction. In MyD88-deficient mice, high levels of T. gondii load were observed in the brain, tongue, heart, lungs, spleen, liver, mesenteric lymph node, and kidneys after infection. The T. gondii load was significantly increased in the lungs in both TLR4- and TLR2-deficient mice compared with WT B6 mice. High levels of anti-mouse heat shock protein (mHSP)70 autoantibody and anti-T. gondii HSP70 antibody production were detected in the sera from MyD88-deficient mice.
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MESH Headings
- Adaptor Proteins, Signal Transducing
- Animals
- Antigens, Differentiation/genetics
- Antigens, Differentiation/immunology
- Antigens, Differentiation/metabolism
- Autoantibodies/biosynthesis
- Autoantibodies/immunology
- Autoantibodies/metabolism
- DNA, Protozoan/chemistry
- DNA, Protozoan/genetics
- Down-Regulation
- Drosophila Proteins
- Enzyme-Linked Immunosorbent Assay
- Membrane Glycoproteins/immunology
- Membrane Glycoproteins/metabolism
- Mice
- Mice, Inbred C57BL
- Mice, Knockout
- Myeloid Differentiation Factor 88
- Polymerase Chain Reaction
- Receptors, Cell Surface/immunology
- Receptors, Cell Surface/metabolism
- Receptors, Immunologic/genetics
- Receptors, Immunologic/immunology
- Receptors, Immunologic/metabolism
- Toll-Like Receptor 2
- Toll-Like Receptor 4
- Toll-Like Receptors
- Toxoplasma/immunology
- Toxoplasma/metabolism
- Toxoplasmosis/immunology
- Toxoplasmosis/metabolism
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Affiliation(s)
- M Chen
- Department of Infection and Host Defense, Graduate School of Medicine, Chiba University, Japan
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371
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Procópio DO, Almeida IC, Torrecilhas ACT, Cardoso JE, Teyton L, Travassos LR, Bendelac A, Gazzinelli RT. Glycosylphosphatidylinositol-Anchored Mucin-Like Glycoproteins from Trypanosoma cruzi Bind to CD1d but Do Not Elicit Dominant Innate or Adaptive Immune Responses Via the CD1d/NKT Cell Pathway. THE JOURNAL OF IMMUNOLOGY 2002; 169:3926-33. [PMID: 12244192 DOI: 10.4049/jimmunol.169.7.3926] [Citation(s) in RCA: 57] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
It has been proposed that self and protozoan-derived GPI anchors are natural ligands of CD1d. In this study, we investigated the ability of GPI anchors from Trypanosoma cruzi to bind to CD1d and mediate activation of NKT cells. We observed that GPI-anchored mucin-like glycoproteins (GPI mucins), glycoinositolphospholipids (GIPLs), and their phosphatidylinositol moieties bind to rCD1d and inhibit the stimulation of a NKT hybridoma by the alpha-galactosylceramide-CD1 complex. However, these GPI anchors and related structures were unable to activate NKT cells in vitro or in vivo. We found that high titers of Ab anti-GPI mucins, but not anti-GIPLs, were detected in sera from wild-type as well as in TAP1(-/-), CD1d(-/-), and MHC class II(-/-) mice after immunization. However, T-dependent anti-GPI mucin Ab isotypes, such as IgG1, IgG2a, IgG2b, and IgG3, were absent on MHC class II(-/-), but were conserved in CD1d(-/-) and TAP1(-/-) mice. Furthermore, we found that CD1d(-/-) mice presented a robust cytokine as well as anti-GPI mucins and anti-GIPL Ab responses, upon infection with T. cruzi parasites. These results indicate that, despite binding to CD1d, GPI mucins and related structures expressed by T. cruzi appear not to evoke dominant CD1d-restricted immune responses in vivo. In contrast, MHC class II is critical for the production of the major Ig G isotypes against GPI mucins from T. cruzi parasites.
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MESH Headings
- Animals
- Antibodies, Protozoan/biosynthesis
- Antibodies, Protozoan/blood
- Antigens, CD1/biosynthesis
- Antigens, CD1/genetics
- Antigens, CD1/metabolism
- Antigens, CD1/physiology
- Antigens, CD1d
- Binding, Competitive/immunology
- Carbohydrate Sequence
- Cells, Cultured
- Chagas Disease/genetics
- Chagas Disease/immunology
- Cytokines/biosynthesis
- Female
- Genetic Predisposition to Disease
- Glycoproteins/metabolism
- Glycoproteins/physiology
- Glycosylphosphatidylinositols/administration & dosage
- Glycosylphosphatidylinositols/chemistry
- Glycosylphosphatidylinositols/metabolism
- Glycosylphosphatidylinositols/physiology
- Immunity, Innate/genetics
- Killer Cells, Natural/immunology
- Killer Cells, Natural/metabolism
- Killer Cells, Natural/parasitology
- Macrophage Activation/genetics
- Macrophage Activation/immunology
- Male
- Mice
- Mice, Inbred C57BL
- Mice, Knockout
- Molecular Sequence Data
- Mucins/administration & dosage
- Mucins/chemistry
- Mucins/metabolism
- Mucins/physiology
- Protozoan Proteins/immunology
- Protozoan Proteins/metabolism
- Signal Transduction/genetics
- Signal Transduction/immunology
- T-Lymphocyte Subsets/immunology
- T-Lymphocyte Subsets/metabolism
- T-Lymphocyte Subsets/parasitology
- Trypanosoma cruzi/chemistry
- Trypanosoma cruzi/immunology
- Trypanosoma cruzi/metabolism
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Affiliation(s)
- Daniela O Procópio
- Department of Biochemistry and Immunology and School of Pharmacy, Federal University of Minas Gerais, Belo Horizonte, Brazil
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372
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Artavanis-Tsakonas K, Riley EM. Innate immune response to malaria: rapid induction of IFN-gamma from human NK cells by live Plasmodium falciparum-infected erythrocytes. JOURNAL OF IMMUNOLOGY (BALTIMORE, MD. : 1950) 2002; 169:2956-63. [PMID: 12218109 DOI: 10.4049/jimmunol.169.6.2956] [Citation(s) in RCA: 237] [Impact Index Per Article: 10.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
To determine the potential contribution of innate immune responses to the early proinflammatory cytokine response to Plasmodium falciparum malaria, we have examined the kinetics and cellular sources of IFN-gamma production in response to human PBMC activation by intact, infected RBC (iRBC) or freeze-thaw lysates of P. falciparum schizonts. Infected erythrocytes induce a more rapid and intense IFN-gamma response from malaria-naive PBMC than do P. falciparum schizont lysates correlating with rapid iRBC activation of the CD3(-)CD56(+) NK cell population to produce IFN-gamma. IFN-gamma(+) NK cells are detectable within 6 h of coculture with iRBC, their numbers peaking at 24 h in most donors. There is marked heterogeneity between donors in magnitude of the NK-IFN-gamma response that does not correlate with mitogen- or cytokine-induced NK activation or prior malaria exposure. The NK cell-mediated IFN-gamma response is highly IL-12 dependent and appears to be partially IL-18 dependent. Exogenous rIL-12 or rIL-18 did not augment NK cell IFN-gamma responses, indicating that production of IL-12 and IL-18 is not the limiting factor explaining differences in NK cell reactivity between donors or between live and dead parasites. These data indicate that NK cells may represent an important early source of IFN-gamma, a cytokine that has been implicated in induction of various antiparasitic effector mechanisms. The heterogeneity of this early IFN-gamma response between donors suggests a variation in their ability to mount a rapid proinflammatory cytokine response to malaria infection that may, in turn, influence their innate susceptibility to malaria infection, malaria-related morbidity, or death from malaria.
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Affiliation(s)
- Katerina Artavanis-Tsakonas
- Department of Infectious and Tropical Diseases, London School of Hygiene and Tropical Medicine, London, United Kingdom
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373
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de Souza JB, Todd J, Krishegowda G, Gowda DC, Kwiatkowski D, Riley EM. Prevalence and boosting of antibodies to Plasmodium falciparum glycosylphosphatidylinositols and evaluation of their association with protection from mild and severe clinical malaria. Infect Immun 2002; 70:5045-51. [PMID: 12183551 PMCID: PMC128284 DOI: 10.1128/iai.70.9.5045-5051.2002] [Citation(s) in RCA: 39] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Glycosylphosphatidylinositols (GPIs), the anchor molecules of some membrane proteins of Plasmodium species, have been implicated in the induction of immunopathology during malaria infections. Hence, neutralization of GPIs by antibodies may reduce the severity of clinical attacks of malaria. To test this hypothesis, we have assessed the levels of anti-GPI antibodies in plasma from children and adults living in areas of seasonal malaria transmission in The Gambia. In a prospective study of susceptibility to clinical or asymptomatic infection, the levels of anti-GPI antibodies were measured before and after the transmission season. Samples were also obtained from children recruited into a hospital-based study of severe malaria. We find that in malaria-exposed individuals both the prevalence and the concentration of anti-GPI antibodies increase with age and that antibody levels are significantly higher at the end of the malaria transmission season than at the start of the season. Antibody levels are also higher in children with asymptomatic infections (i.e., those with a degree of clinical immunity) than in children who developed clinical malaria and high parasitemia, although this difference is not statistically significant. Importantly, antibodies appear to be rapidly boosted by clinical malaria infection, but children under the age of two years are seronegative for anti-GPI antibodies, even during an acute infection. While GPIs may be involved in the pathogenesis of human malaria, the data from this study do not provide any strong evidence to support the notion that anti-GPI antibodies confer resistance to mild or severe malarial disease. Further case-control studies, ideally of a prospective nature, are required to elucidate the role of antiglycolipid antibodies in protection from severe malaria.
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Affiliation(s)
- J Brian de Souza
- Department of Immunology and Molecular Pathology, Royal Free and University College London Medical School, London W1T 4JF, United Kingdom.
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374
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Abstract
There is increased recognition that dendritic cells (DCs) are an important source of the IL-12 required to initiate protective immunity to protozoa, such as Leishmania and Toxoplasma. This article reviews the advances made in the last two years in understanding the pathways that lead to DC activation after infection with these organisms. Interestingly, there appear to be differences in the DC activation pathways utilized by these two intracellular protozoa which also may differ from the pathways utilized by bacteria.
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Affiliation(s)
- Phillip Scott
- Department of Pathobiology, School of Veterinary Medicine, University of Pennsylvania, 3800 Spruce Street, Philadelphia, PA 19104, USA.
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375
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Abstract
The Toll-like receptor (TLR) family plays a role in sensing invading pathogens. Ten members have been reported to date, seven of which were found to recognize discrete bacterial components. Mouse models lacking each TLR and its signaling molecule are useful tools for the analysis of the innate immune system.
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Affiliation(s)
- Osamu Takeuchi
- Department of Host Defense, Research Institute for Microbial Diseases, Osaka University, 3-1 Yamada-oka, Suita, Osaka, Japan
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376
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Pacheco-Tena C, Zhang X, Stone M, Burgos-Vargas R, Inman RD. Innate immunity in host-microbial interactions: beyond B27 in the spondyloarthropathies. Curr Opin Rheumatol 2002; 14:373-82. [PMID: 12118170 DOI: 10.1097/00002281-200207000-00007] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023]
Abstract
The spondyloarthropathies are diseases influenced by genetic predisposition and, to a varying extent, infectious triggers. A causal role for bacterial infections is most clear for reactive arthritis. Recent insights into arthritogenic components of bacteria may set the stage for a better understanding of disease pathogenesis, the role of heat shock proteins in antigen processing and immune activation, and the adjuvant effect of CpG-DNA. Recent developments in the area of innate immunity broaden current concepts of genetically defined factors in host-pathogen interactions. In particular, the biology of toll-like receptors as important elements in the innate immune response to pathogens is being defined. These factors in innate immunity may have important implications for sequelae of infections, such as reactive arthritis.
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Affiliation(s)
- César Pacheco-Tena
- Arthritis Center of Excellence, Toronto Western Hospital, Toronto, Ontario, Canada.
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377
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Sabroe I, Parker LC, Wilson AG, Whyte MKB, Dower SK. Toll-like receptors: their role in allergy and non-allergic inflammatory disease. Clin Exp Allergy 2002; 32:984-9. [PMID: 12100042 DOI: 10.1046/j.1365-2745.2002.01451.x] [Citation(s) in RCA: 62] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/23/2023]
Abstract
The human TLRs comprise an important and interesting group of receptors that regulate pathogen-related responses, and play as yet uncharacterized roles in the amplication of sterile inflammation. Signalling through these receptors, which are powerfully coupled in gene transcription processes, has powerful immunostimulatory and immunomodulatory effects. Exploitation of TLR signalling will probably lead to novel effective therapies for allergic disease, in the first instance through more efficient mechanisms of immunotherapy. The likelihood of adverse consequences of such treatments, though possible, may be minimized by use of conjugated vaccines.
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Affiliation(s)
- I Sabroe
- Section of Functional Genomics, Division of Genomic Medicine, University of Sheffield, Sheffield, UK.
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378
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Caamaño J, Hunter CA. NF-kappaB family of transcription factors: central regulators of innate and adaptive immune functions. Clin Microbiol Rev 2002; 15:414-29. [PMID: 12097249 PMCID: PMC118079 DOI: 10.1128/cmr.15.3.414-429.2002] [Citation(s) in RCA: 383] [Impact Index Per Article: 17.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023] Open
Abstract
Transcription factors of the Rel/NF-kappaB family are activated in response to signals that lead to cell growth, differentiation, and apoptosis, and these proteins are critical elements involved in the regulation of immune responses. The conservation of this family of transcription factors in many phyla and their association with antimicrobial responses indicate their central role in the regulation of innate immunity. This is illustrated by the association of homologues of NF-kappaB, and their regulatory proteins, with resistance to infection in insects and plants (M. S. Dushay, B. Asling, and D. Hultmark, Proc. Natl. Acad. Sci. USA 93:10343-10347, 1996; D. Hultmark, Trends Genet. 9:178-183, 1993; J. Ryals et al., Plant Cell 9:425-439, 1997). The aim of this review is to provide a background on the biology of NF-kappaB and to highlight areas of the innate and adaptive immune response in which these transcription factors have a key regulatory function and to review what is currently known about their roles in resistance to infection, the host-pathogen interaction, and development of human disease.
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Affiliation(s)
- Jorge Caamaño
- Department of Pathobiology, University of Pennsylvania, Philadelphia, Pennsylvania 19104-6008, USA
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379
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Takeuchi O, Sato S, Horiuchi T, Hoshino K, Takeda K, Dong Z, Modlin RL, Akira S. Cutting edge: role of Toll-like receptor 1 in mediating immune response to microbial lipoproteins. JOURNAL OF IMMUNOLOGY (BALTIMORE, MD. : 1950) 2002; 169:10-4. [PMID: 12077222 DOI: 10.4049/jimmunol.169.1.10] [Citation(s) in RCA: 927] [Impact Index Per Article: 42.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/19/2023]
Abstract
The Toll-like receptor (TLR) family acts as pattern recognition receptors for pathogen-specific molecular patterns (PAMPs). TLR2 is essential for the signaling of a variety of PAMPs, including bacterial lipoprotein/lipopeptides, peptidoglycan, and GPI anchors. TLR6 associates with TLR2 and recognizes diacylated mycoplasmal lipopeptide along with TLR2. We report here that TLR1 associates with TLR2 and recognizes the native mycobacterial 19-kDa lipoprotein along with TLR2. Macrophages from TLR1-deficient (TLR1(-/-)) mice showed impaired proinflammatory cytokine production in response to the 19-kDa lipoprotein and a synthetic triacylated lipopeptide. In contrast, TLR1(-/-) cells responded normally to diacylated lipopeptide. TLR1 interacts with TLR2 and coexpression of TLR1 and TLR2 enhanced the NF-kappaB activation in response to a synthetic lipopeptide. Furthermore, lipoprotein analogs whose acylation was modified were preferentially recognized by TLR1. Taken together, TLR1 interacts with TLR2 to recognize the lipid configuration of the native mycobacterial lipoprotein as well as several triacylated lipopeptides.
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MESH Headings
- Acylation
- Adjuvants, Immunologic/deficiency
- Adjuvants, Immunologic/genetics
- Adjuvants, Immunologic/physiology
- Animals
- Bacterial Proteins/chemical synthesis
- Bacterial Proteins/immunology
- Bacterial Proteins/metabolism
- Cell Line
- Crosses, Genetic
- Drosophila Proteins
- Female
- Humans
- Lipoproteins/chemical synthesis
- Lipoproteins/immunology
- Lipoproteins/metabolism
- Macrophages, Peritoneal/immunology
- Macrophages, Peritoneal/metabolism
- Male
- Membrane Glycoproteins/deficiency
- Membrane Glycoproteins/genetics
- Membrane Glycoproteins/metabolism
- Membrane Glycoproteins/physiology
- Mice
- Mice, Inbred C57BL
- Mice, Knockout
- Molecular Weight
- Mycobacterium/immunology
- Peptides/chemical synthesis
- Peptides/immunology
- Peptides/metabolism
- Receptors, Cell Surface/deficiency
- Receptors, Cell Surface/genetics
- Receptors, Cell Surface/metabolism
- Receptors, Cell Surface/physiology
- Toll-Like Receptor 1
- Toll-Like Receptor 2
- Toll-Like Receptors
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Affiliation(s)
- Osamu Takeuchi
- Department of Host Defense, Research Institute for Microbial Diseases, Osaka University, Suita, Japan
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380
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Channe Gowda D. Structure and activity of glycosylphosphatidylinositol anchors of Plasmodium falciparum. Microbes Infect 2002; 4:983-90. [PMID: 12106792 DOI: 10.1016/s1286-4579(02)01619-2] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
Abstract
The glycosylphosphatidylinositol (GPI) anchors of Plasmodium falciparum are thought to be etiologic agents of malaria based on their ability to induce proinflammatory cytokine production by macrophages and cause symptoms that resemble severe malaria illness in animals. This review summarizes the published information on the structures of P. falciparum GPIs, structure-activity relationship, and anti-GPI antibodies in the host.
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Affiliation(s)
- D Channe Gowda
- Department of Biochemistry and Molecular Biology, The Pennsylvania State University College of Medicine, 500 University Drive, Hershey, PA 17033, USA.
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381
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Teixeira MM, Almeida IC, Gazzinelli RT. Introduction: innate recognition of bacteria and protozoan parasites. Microbes Infect 2002; 4:883-6. [PMID: 12106780 DOI: 10.1016/s1286-4579(02)01625-8] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
Major advances have recently been achieved in the area of microbial recognition by the innate immune system. In this Forum, we discuss important issues related to innate recognition of bacteria and protozoan parasites. In particular, we highlight the structural characterization of pathogen-associated molecular patterns (PAMPs); the definition of the receptors required for recognition of PAMPs, especially the Toll-like receptors (TLRs); the signaling pathways triggered by PAMPs/PAMPs receptor interaction; and the functional consequences of these interactions for pathogenesis during microbial infection.
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Affiliation(s)
- Mauro M Teixeira
- Department of Biochemistry and Immunology, ICB, UFMG, Av. Antônio Carlos 6627, MG, Belo Horizonte, Brazil
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382
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Magez S, Stijlemans B, Baral T, De Baetselier P. VSG-GPI anchors of African trypanosomes: their role in macrophage activation and induction of infection-associated immunopathology. Microbes Infect 2002; 4:999-1006. [PMID: 12106794 DOI: 10.1016/s1286-4579(02)01617-9] [Citation(s) in RCA: 54] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
Abstract
African trypanosomes express a glycosylphosphatidyl inositol (GPI)-anchored variant-specific surface glycoprotein (VSG) as a protective coat. During infection, large amounts of VSG molecules are released into the circulation. Their interaction with various cells of the immune system underlies the severe infection-associated pathology. Recent results have shown that anti-GPI vaccination can prevent the occurrence of this pathology.
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Affiliation(s)
- Stefan Magez
- Laboratory of Cellular Immunology, Free University of Brussels/Flemish Interuniversity, Institute for Biotechnology, Paardenstraat 65, Sint Genesius Rode, Belgium.
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383
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DosReis GA, Peçanha LMT, Bellio M, Previato JO, Mendonça-Previato L. Glycoinositol phospholipids from Trypanosoma cruzi transmit signals to the cells of the host immune system through both ceramide and glycan chains. Microbes Infect 2002; 4:1007-13. [PMID: 12106795 DOI: 10.1016/s1286-4579(02)01616-7] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Abstract
Chagas' disease is a chronic disease affecting millions of people in Latin America. The cell surface of Trypanosoma cruzi, the etiological agent, is covered by a glycocalyx whose components play important roles in parasite survival and infectivity. The most abundant surface component is a glycolipid (glycoinositol phospholipid, GIPL) related in structure to glycosylphosphatidyl inositol anchors. In this review, we describe the biological effects of highly purified native GIPLs and their glycan or lipid moities on cells of the host immune system.
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Affiliation(s)
- George A DosReis
- Instituto de Biofísica Carlos Chagas Filho, Centro de Ciências da Saúde, Bloco G, Universidade Federal do Rio de Janeiro, Cidade Universitária, Ilha do Fundão, Rio de Janeiro, Brazil
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384
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Ropert C, Ferreira LRP, Campos MAS, Procópio DO, Travassos LR, Ferguson MAJ, Reis LFL, Teixeira MM, Almeida IC, Gazzinelli RT. Macrophage signaling by glycosylphosphatidylinositol-anchored mucin-like glycoproteins derived from Trypanosoma cruzi trypomastigotes. Microbes Infect 2002; 4:1015-25. [PMID: 12106796 DOI: 10.1016/s1286-4579(02)01609-x] [Citation(s) in RCA: 59] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
Abstract
Activation of cells from the innate immune system has an important role in host resistance to early infection with the intracellular protozoan parasite, Trypanosoma cruzi. Here we review the studies that have identified and structurally characterized the glycosylphosphatidylinositol (GPI) anchors, as parasite molecules responsible for the activation of cells from the macrophage lineage. We also cover the studies that have identified the receptor, signaling pathways as well as the array of genes expressed in macrophages that are activated by these glycoconjugates. We discuss the possible implications of such response on the host resistance to T. cruzi infection and the pathogenesis of Chagas disease.
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Affiliation(s)
- Catherine Ropert
- Laboratory of Immunopathology, CPqRR-FIOCRUZ, Av. Augusto de Lima 1715, MG, Belo Horizonte, Brazil
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385
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Brodskyn C, Patricio J, Oliveira R, Lobo L, Arnholdt A, Mendonça-Previato L, Barral A, Barral-Netto M. Glycoinositolphospholipids from Trypanosoma cruzi interfere with macrophages and dendritic cell responses. Infect Immun 2002; 70:3736-43. [PMID: 12065516 PMCID: PMC128086 DOI: 10.1128/iai.70.7.3736-3743.2002] [Citation(s) in RCA: 57] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022] Open
Abstract
To investigate the possible effects of glycoinositolphospholipid (GIPL) from Trypanosoma cruzi on human antigen presenting cells, we tested their effects on lipopolysaccharide (LPS)-stimulated human macrophages and dendritic cells (DC). Human macrophages or DC were incubated with GIPL (50 microg/ml) and LPS (500 pg/ml) and tumor necrosis factor alpha (TNF-alpha), interleukin 8 (IL-8), IL-10, and IL-12p40 levels in supernatants were analyzed by enzyme-linked immunosorbent assay. TNF-alpha, IL-10, and IL-12 secretion were significantly decreased by GIPL both in macrophages and DC. In contrast, GIPL did not alter IL-8 production. We also analyzed the expression of CD80, CD86, HLA-DR, CD40, and CD57 on the macrophage surface after stimulation with LPS in the presence or absence of T. cruzi GIPL. GIPL led to a down-regulation in the expression of all tested molecules. We additionally examined the influence of T. cruzi GIPL on the response of human DC to LPS. LPS-induced HLA-DR, CD83, and CD86 up-regulation was significantly inhibited by GIPL. A slight down-regulation in CD80 and CD40 expression on DC surfaces in the presence of GIPL was also noticed. Similarly, GIPL led to down-modulation of CD83, CD80, CD86, and HLA-DR surface expression and TNF-alpha and IL-10 production when DC were stimulated by CD40L. The ceramide portion of GIPL was responsible for most of the activity exhibited by the whole molecule. Considering the important role of the immune response in determining the fate of the host-parasite relationship, the immunoregulatory activities of T. cruzi GIPL are potentially important for parasite evasion and then pathogenesis of infection with protozoan parasites.
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Affiliation(s)
- Claudia Brodskyn
- Centro de Pesquisa Gonçalo Moniz, FIOCRUZ, Instituto de Ciências da Saúde, Universidade Federal Bahia, Salvador, Brazil
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386
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Ouaissi A, Guilvard E, Delneste Y, Caron G, Magistrelli G, Herbault N, Thieblemont N, Jeannin P. The Trypanosoma cruzi Tc52-released protein induces human dendritic cell maturation, signals via Toll-like receptor 2, and confers protection against lethal infection. JOURNAL OF IMMUNOLOGY (BALTIMORE, MD. : 1950) 2002; 168:6366-74. [PMID: 12055254 DOI: 10.4049/jimmunol.168.12.6366] [Citation(s) in RCA: 106] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Abstract
The intracellular protozoan parasite Trypanosoma cruzi is the etiological agent of Chagas disease. We have recently identified a T. cruzi-released protein related to thiol-disulfide oxidoreductase family, called Tc52, which is crucial for parasite survival and virulence. In vitro, Tc52 in combination with IFN-gamma activates human macrophages. In vivo, active immunization with Tc52 relieves the immunosuppression associated to acute infection and elicits a specific immune response. As dendritic cells (DC) have a central role in the initiation of immune responses, we investigated whether Tc52 may modulate DC activity. We show that Tc52 induces human DC maturation. Tc52-treated immature DC acquire CD83 and CD86 expression, produce inflammatory chemokines (IL-8, monocyte chemoattractant protein-1, and macrophage-inflammatory protein-1 alpha), and present potent costimulatory properties. Tc52 binds to DC by a mechanism with the characteristics of a saturable receptor system and signals via Toll-like receptor 2. While Tc52-mediated signaling involves its reduced glutathione-binding site, another portion of the molecule is involved in Tc52 binding to DC. Finally, we report that immunization with Tc52 protects mice in vivo against lethal infection with T. cruzi. Together these data evidence complex molecular interactions between the T. cruzi-derived molecule, Tc52, and DC, and suggest that Tc52 and related class of proteins might represent a new type of pathogen-associated molecular patterns. Moreover, the immune protection data suggest that Tc52 is among candidate molecules that may be used to design an optimal multicomponent vaccine to control T. cruzi infection.
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Affiliation(s)
- Ali Ouaissi
- Institut de Recherche pour le Développement UR 008, Montpellier, France.
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387
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Scanga CA, Aliberti J, Jankovic D, Tilloy F, Bennouna S, Denkers EY, Medzhitov R, Sher A. Cutting edge: MyD88 is required for resistance to Toxoplasma gondii infection and regulates parasite-induced IL-12 production by dendritic cells. JOURNAL OF IMMUNOLOGY (BALTIMORE, MD. : 1950) 2002; 168:5997-6001. [PMID: 12055206 DOI: 10.4049/jimmunol.168.12.5997] [Citation(s) in RCA: 355] [Impact Index Per Article: 16.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
Host resistance to the intracellular protozoan Toxoplasma gondii is highly dependent on early IL-12 production by APC. We demonstrate here that both host resistance and T. gondii-induced IL-12 production are dramatically reduced in mice lacking the adaptor molecule MyD88, an important signaling element used by Toll-like receptor (TLR) family members. Infection of MyD88-deficient mice with T. gondii resulted in uncontrolled parasite replication and greatly reduced plasma IL-12 levels. Defective IL-12 responses to T. gondii Ags (soluble tachyzoite Ag (STAg)) were observed in MyD88(-/-) peritoneal macrophages, neutrophils, and splenic dendritic cells (DC). In contrast, DC from TLR2- or TLR4-deficient animals developed normal IL-12 responses to STAg. In vivo treatment with pertussis toxin abolished the residual IL-12 response displayed by STAg-stimulated DC from MyD88(-/-) mice. Taken together, these data suggest that the induction of IL-12 by T. gondii depends on a unique mechanism involving both MyD88 and G protein-coupled signaling pathways.
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MESH Headings
- Adaptor Proteins, Signal Transducing
- Animals
- Antigens, Differentiation/genetics
- Antigens, Differentiation/physiology
- Dendritic Cells/immunology
- Dendritic Cells/metabolism
- Dendritic Cells/parasitology
- Drosophila Proteins
- Female
- Immunity, Innate/genetics
- Interferon-gamma/biosynthesis
- Interferon-gamma/deficiency
- Interleukin-12/biosynthesis
- Interleukin-12/deficiency
- Macrophages, Peritoneal/immunology
- Macrophages, Peritoneal/metabolism
- Macrophages, Peritoneal/parasitology
- Male
- Membrane Glycoproteins/deficiency
- Membrane Glycoproteins/physiology
- Mice
- Mice, Inbred C57BL
- Mice, Knockout
- Myeloid Differentiation Factor 88
- Neutrophils/immunology
- Neutrophils/metabolism
- Neutrophils/parasitology
- Receptors, CCR5/physiology
- Receptors, Cell Surface/deficiency
- Receptors, Cell Surface/physiology
- Receptors, Immunologic/deficiency
- Receptors, Immunologic/genetics
- Receptors, Immunologic/physiology
- Signal Transduction/immunology
- Toll-Like Receptor 2
- Toll-Like Receptor 4
- Toll-Like Receptors
- Toxoplasma/immunology
- Toxoplasmosis, Animal/genetics
- Toxoplasmosis, Animal/immunology
- Toxoplasmosis, Animal/mortality
- Toxoplasmosis, Animal/parasitology
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Affiliation(s)
- Charles A Scanga
- Laboratory of Parasitic Diseases, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, MD 20892, USA.
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388
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Abstract
The innate immune system is a universal and ancient form of host defense against infection. Innate immune recognition relies on a limited number of germline-encoded receptors. These receptors evolved to recognize conserved products of microbial metabolism produced by microbial pathogens, but not by the host. Recognition of these molecular structures allows the immune system to distinguish infectious nonself from noninfectious self. Toll-like receptors play a major role in pathogen recognition and initiation of inflammatory and immune responses. Stimulation of Toll-like receptors by microbial products leads to the activation of signaling pathways that result in the induction of antimicrobial genes and inflammatory cytokines. In addition, stimulation of Toll-like receptors triggers dendritic cell maturation and results in the induction of costimulatory molecules and increased antigen-presenting capacity. Thus, microbial recognition by Toll-like receptors helps to direct adaptive immune responses to antigens derived from microbial pathogens.
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Affiliation(s)
- Charles A Janeway
- Section of Immunobiology and Howard Hughes Medical Institute, Yale University School of Medicine, New Haven, Connecticut 06520-8011, USA.
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389
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Abstract
The phagocytic response of innate immune cells such as macrophages is defined by the activation of complex signaling networks that are stimulated by microbial contact. Many individual proteins have been demonstrated to participate in phagocytosis, and the application of high-throughput tools has indicated that many more remain to be described. In this review, we examine this complexity and describe how during recognition, multiple receptors are simultaneously engaged to mediate internalization, activate microbial killing, and induce the production of inflammatory cytokines and chemokines. Many signaling molecules perform multiple functions during phagocytosis, and these molecules are likely to be key regulators of the process. Indeed, pathogenic microorganisms target many of these molecules in their attempts to evade destruction.
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Affiliation(s)
- David M Underhill
- Institute for Systems Biology, 1441 North 34 Street, Seattle, Washington 98103, USA.
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390
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Abstract
OBJECTIVE To review the role of mammalian Toll-like receptors (TLRs) in host defense. DATE SOURCES MEDLINE search and current literature. RESULTS First, TLRs participate in the recognition of molecular patterns present on microorganisms. Second, TLRs are expressed at the interface with the environment, the site of microbial invasion. Third, activation of TLRs induces expression of costimulatory molecules and the release of cytokines that instruct the adaptive immune response. Fourth, activation of TLRs leads to direct antimicrobial effector pathways that can result in elimination of the foreign invader. CONCLUSIONS Maintained throughout evolution, mammalian TLRs are proteins that participate in innate immunity to microbial pathogens. Insights into TLR activation pathways provide new therapeutic targets for intervention in infectious and immunologic disease.
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Affiliation(s)
- Robert L Modlin
- Department of Medicine, Molecular Biology Institute, UCLA School of Medicine, Los Angeles, California 90095, USA.
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391
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Abstract
The inflammatory response that follows the infection with Trypanosoma cruzi is essential for host resistance to infection but is also responsible for the diverse pathology observed in Chagas disease. Here, we examine the stimuli and mechanisms underlying chemokine production following infection in vitro and in vivo, and the ability of chemokines to coordinate the influx of inflammatory and immune cells to the site of parasite infection, and to control T. cruzi growth.
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Affiliation(s)
- Mauro M Teixeira
- Departmento Bioquímica e Imunologia, Instituto de Ciências Biológicas, Universidade Federal de Minas Gerais, Av. Antônio Carlos, 6627, Pampulha, 31270-901, Belo Horizonte, MG, Brazil.
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392
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Coelho PS, Klein A, Talvani A, Coutinho SF, Takeuchi O, Akira S, Silva JS, Canizzaro H, Gazzinelli RT, Teixeira MM. Glycosylphosphatidylinositol‐anchored mucin‐like glycoproteins isolated from
Trypanosoma cruzi
trypomastigotes induce in vivo leukocyte recruitment dependent on MCP‐1 production by IFN‐γ‐primed‐macrophages. J Leukoc Biol 2002. [DOI: 10.1189/jlb.71.5.837] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022] Open
Affiliation(s)
- Patrícia S. Coelho
- Departamento de Bioquímica e Imunologia, Instituto de Ciências Biológicas, Universidade Federal de Minas Gerais, Belo Horizonte, MG, Brazil
| | - André Klein
- Departamento de Bioquímica e Imunologia, Instituto de Ciências Biológicas, Universidade Federal de Minas Gerais, Belo Horizonte, MG, Brazil
| | - André Talvani
- Departamento de Bioquímica e Imunologia, Instituto de Ciências Biológicas, Universidade Federal de Minas Gerais, Belo Horizonte, MG, Brazil
| | - Sibele F. Coutinho
- Departamento de Bioquímica e Imunologia, Instituto de Ciências Biológicas, Universidade Federal de Minas Gerais, Belo Horizonte, MG, Brazil
| | - Osamu Takeuchi
- Department of Host Defense, Research Institute for Microbial Diseases, Osaka University, Japan
| | - Shizuo Akira
- Department of Host Defense, Research Institute for Microbial Diseases, Osaka University, Japan
| | - João S. Silva
- Departamento de Imunologia, Universidade de São Paulo, Ribeirão Preto, Brazil; and
| | - Hélia Canizzaro
- Departamento de Bioquímica e Imunologia, Instituto de Ciências Biológicas, Universidade Federal de Minas Gerais, Belo Horizonte, MG, Brazil
| | - Ricardo T. Gazzinelli
- Departamento de Bioquímica e Imunologia, Instituto de Ciências Biológicas, Universidade Federal de Minas Gerais, Belo Horizonte, MG, Brazil
- Centro de Pesquisas René Rachou, Fundação Oswaldo Cruz, Belo Horizonte, MG, Brazil
| | - Mauro M. Teixeira
- Departamento de Bioquímica e Imunologia, Instituto de Ciências Biológicas, Universidade Federal de Minas Gerais, Belo Horizonte, MG, Brazil
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393
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Brake DA. Vaccinology for control of apicomplexan parasites: a simplified language of immune programming and its use in vaccine design. Int J Parasitol 2002; 32:509-15. [PMID: 11943223 DOI: 10.1016/s0020-7519(01)00353-8] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/27/2023]
Abstract
Most mammalian immune systems and parasites have co-evolved over the millennia, interacting within a common environment and communicating through a common language. This language is comprised of copious dialects in which a variety of host innate and acquired immune pathways actively interact with a multitude of parasite-specific survival strategies. Nonetheless, a simplified language is likely present since the same basic molecular and cellular mechanisms are associated with resistance or susceptibility to parasite infection. Protective immunity against protozoa within the phylum Apicomplexa (e.g. Cryptosporidia, Eimeria, Neospora, Plasmodia and Toxoplasma) is generally CD4+ T cell-dependent and elicited along the IL-12/IFN-gamma/iNOS effector axis. This simplified language can be decoded in part by significant advances in understanding naïve T cell activation, differentiation and generation of immunologic memory. Vaccine adjuvants and new immunisation strategies for generation of more potent immunity can also be viewed through this common language lens. The aim of this paper is to summarise recently published fundamental immunology studies, their relevance through examples in specific coccidian-host immune dialects, and how this simplified language can be used for the more rationale design of parasite vaccine control strategies.
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Affiliation(s)
- David A Brake
- Veterinary Medicine Biological Discovery, Pfizer Global Research and Development, Pfizer Inc., MS 8118-C2, Groton, CT 06340, USA.
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394
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Fox‐Marsh A, Harrison LC. Emerging evidence that molecules expressed by mammalian tissue grafts are recognized by the innate immune system. J Leukoc Biol 2002. [DOI: 10.1189/jlb.71.3.401] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022] Open
Affiliation(s)
- Annette Fox‐Marsh
- Autoimmunity and Transplantation Division, The Walter and Eliza Hall Institute of Medical Research, Parkville, Australia
| | - Leonard C. Harrison
- Autoimmunity and Transplantation Division, The Walter and Eliza Hall Institute of Medical Research, Parkville, Australia
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395
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Abstract
The ability of a host to sense invasion by pathogenic organisms and to respond appropriately to control infection is paramount to survival. In the case of sepsis and septic shock, however, an exaggerated systemic response may, in fact, contribute to the morbidity and mortality associated with overwhelming infections. The innate immune system has evolved as the first line of defense against invading microorganisms. The Toll-like receptors (TLRs) are a part of this innate immune defense, recognizing conserved patterns on microorganisms. These TLRs and their signaling pathways are represented in such diverse creatures as mammals, fruit flies, and plants. Ten members of the TLR family have been identified in humans, and several of them appear to recognize specific microbial products, including lipopolysaccharide, bacterial lipoproteins, peptidoglycan, and bacterial DNA. Signals initiated by the interaction of TLRs with specific microbial patterns direct the subsequent inflammatory response. Thus, TLR signaling represents a key component of the innate immune response to microbial infection.
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396
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Abstract
The mammalian Toll-like receptors (TLRs) are expressed on macrophages and dendritic cells, which are primarily involved in innate immunity. At present, ligands for several of the TLRs, such as TLR2, TLR3, TLR4, TLR5, TLR6, and TLR9, have been identified. Most of these ligands are derived from pathogens, but not found in the host, suggesting that the TLRs are critical to sensing invading microorganisms. Pathogen recognition by TLRs provokes rapid activation of innate immunity by inducing production of proinflammatory cytokines and upregulation of costimulatory molecules. Activated innate immunity subsequently leads to effective adaptive immunity. In this regard, the TLRs are considered to be adjuvant receptors. Distinct TLRs can exert distinct, but overlapping sets of biological effects. Accumulating evidence indicates that this can be attributed to both the common and unique aspects of the signaling mechanisms that mediate TLR family responses. For example, TLR2 and TLR9 require MyD88 as an essential signal transducer, whereas TLR4 can induce costimulatory molecule upregulation in a MyD88-independent manner. Understanding the TLR system should offer invaluable opportunity for manipulating host immune responses.
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Affiliation(s)
- Tsuneyasu Kaisho
- Department of Host Defense, Research Institute for Microbial Diseases, Osaka University, Osaka, Japan
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397
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Abstract
Toll-like receptors are pattern-recognition receptors that have key roles in detecting microbes and initiating inflammatory responses. Recently, a host of new microbial products that activate specific Toll-like receptors have been defined, and additional components that mediate intracellular signaling have been identified. There has also been greater recognition of the importance of specific Toll-like receptors in host defense.
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Affiliation(s)
- David M Underhill
- Institute for Systems Biology, 4225 Roosevelt Way NE, Seattle, WA 98105, USA.
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398
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Adachi K, Tsutsui H, Kashiwamura S, Seki E, Nakano H, Takeuchi O, Takeda K, Okumura K, Van Kaer L, Okamura H, Akira S, Nakanishi K. Plasmodium berghei infection in mice induces liver injury by an IL-12- and toll-like receptor/myeloid differentiation factor 88-dependent mechanism. JOURNAL OF IMMUNOLOGY (BALTIMORE, MD. : 1950) 2001; 167:5928-34. [PMID: 11698470 DOI: 10.4049/jimmunol.167.10.5928] [Citation(s) in RCA: 162] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
Abstract
Malaria, caused by infection with Plasmodium spp., is a life cycle-specific disease that includes liver injury at the erythrocyte stage of the parasite. In this study, we have investigated the mechanisms underlying Plasmodium berghei-induced liver injury, which is characterized by the presence of apoptotic and necrotic hepatocytes and dense infiltration of lymphocytes. Although both IL-12 and IL-18 serum levels were elevated after infection, IL-12-deficient, but not IL-18-deficient, mice were resistant to liver injury induced by P. berghei. Neither elevation of serum IL-12 levels nor liver injury was observed in mice deficient in myeloid differentiation factor 88 (MyD88), an adaptor molecule shared by Toll-like receptors (TLRs). These results demonstrated a requirement of the TLR-MyD88 pathway for induction of IL-12 production during P. berghei infection. Hepatic lymphocytes from P. berghei-infected wild-type mice lysed hepatocytes from both uninfected and infected mice. The hepatocytotoxic action of these cells was blocked by a perforin inhibitor but not by a neutralizing anti-Fas ligand Ab and was up-regulated by IL-12. Surprisingly, these cells killed hepatocytes in an MHC-unrestricted manner. However, CD1d-deficient mice that lack CD1d-restricted NK T cells, were susceptible to liver injury induced by P. berghei. Collectively, our results indicate that the liver injury induced by P. berghei infection of mice induces activation of the TLR-MyD88 signaling pathway which results in IL-12 production and activation of the perforin-dependent cytotoxic activities of MHC-unrestricted hepatic lymphocytes.
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MESH Headings
- Adaptor Proteins, Signal Transducing
- Animals
- Antigens, CD1/analysis
- Antigens, CD1d
- Antigens, Differentiation/genetics
- Antigens, Differentiation/physiology
- Cytotoxicity Tests, Immunologic
- Drosophila Proteins
- Fas Ligand Protein
- Female
- Hepatitis, Animal/etiology
- Hepatitis, Animal/parasitology
- Hepatitis, Animal/pathology
- Interleukin-12/genetics
- Interleukin-12/physiology
- Interleukin-18/genetics
- Interleukin-18/physiology
- Killer Cells, Natural/immunology
- Liver/pathology
- Malaria/etiology
- Malaria/pathology
- Membrane Glycoproteins/genetics
- Membrane Glycoproteins/physiology
- Mice
- Mice, Knockout
- Myeloid Differentiation Factor 88
- Perforin
- Plasmodium berghei
- Pore Forming Cytotoxic Proteins
- Receptors, Cell Surface/physiology
- Receptors, Immunologic
- T-Lymphocyte Subsets/immunology
- Toll-Like Receptors
- fas Receptor/physiology
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Affiliation(s)
- K Adachi
- Department of Immunology and Medical Zoology, Institute for Advanced Medical Science, Hyogo College of Medicine, Nishinomiya, Hyogo, Japan
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399
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Abstract
Toll-like receptors have a crucial role in the detection of microbial infection in mammals and insects. In mammals, these receptors have evolved to recognize conserved products unique to microbial metabolism. This specificity allows the Toll proteins to detect the presence of infection and to induce activation of inflammatory and antimicrobial innate immune responses. Recognition of microbial products by Toll-like receptors expressed on dendritic cells triggers functional maturation of dendritic cells and leads to initiation of antigen-specific adaptive immune responses.
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Affiliation(s)
- R Medzhitov
- Section of Immunobiology, Yale University School Medicine, and Howard Hughes Medical Institute, New Haven, Connecticut 06520, USA.
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400
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Almeida IC, Gazzinelli RT. Proinflammatory activity of glycosylphosphatidylinositol anchors derived from
Trypanosoma cruzi
: structural and functional analyses. J Leukoc Biol 2001. [DOI: 10.1189/jlb.70.4.467] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022] Open
Affiliation(s)
- Igor C. Almeida
- Department of Parasitology, University of São Paulo, São Paulo, SP, Brazil; and
| | - Ricardo T. Gazzinelli
- Department of Biochemistry and Immunology, Federal University of Minas Gerais, Belo Horizonte, MG, Brazil
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